Biochem II Test 2

Which of the following compounds incorporates second nitrogen atom of urea in urea cycle?

Aspartate

Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle?

Aspartate

Which of the following compounds can activate phospholipase A2 in order to release the precursor molecule for eicosanoid biosynthesis?

Histamine

Which of the following compounds is nutritionally essential dietary source of arachidonates in humans?

Linoleate

Glutamate produced within other tissues must be transported to _______________ for urea production.

Liver

Which substance is not involved in the production of urea from NH4+ via the urea cycle?

Malate

Which of the following functional groups is transferred by S-adenosylmethionine (SAM) to produce epinephrine from norepinephrine?

Methyl group (- CH3)

Which of the following enzymes is the rate-limiting enzyme in urea biosynthesis?

Mitochondrial carbamoyl phosphate synthetase I

Which of the following is an allosteric activator of mammalian carbamoyl phosphate synthetase?

N-acetylglutamate

Which is the most stable and most reduced form of tetrahydrofolate (THF) carrying a one-carbon group?

N5-methyl-THF

What is the reducing agent in single carbon group transfer

NADH

Which of the following reaction products contributes and incorporates the first nitrogen atom in urea?

NH4+ ion

Amino acid catabolism involves the breakdown of 20 amino acids all of which contain nitrogen but have different carbon skeletons. What overall strategy is used to deal with this problem?

Nitrogen is removed by transamination to glutamate.

Which of the following serves as the precursor to synthesize both prostaglandins and thromboxanes?

PGH2

Aspirin prevents the production of

PGH2 which is the precursor thromboxine and prostaglandins

Molecules responsible for single carbon group transfer

THF(tetrahydroflouride) and SAM

what enzyme regenerates THF

Thymidylate synthase

How many amino group(s) is/are present in urea?

Two

Which of the following compounds is needed for the rearrangement of the methyl group of L-methylmalonyl-CoA to form succinyl-CoA?

Vitamin B12

The common compound generated during the oxidative degradation of amino acids, fatty acids and glucose is

acetyl-CoA

aspirin inhibits COX enzyme by

adding acetyl group to it( permanent)

enzyme in the transfer of methyl group from methylamalonyl-CoA to succinyl-CoA

adenosyl cobalamin

PGH2 is a precursor to

all other prostaglandins and thromboxane

During amino acid metabolism glutamate releases its _________ group as ________ in the ________.

amino, ammonia, liver

where do the Nitrogens in Urea come from

ammonium ion and apartic acid

oxidation of amino acids releases

ammonium ion, NH4+

Eicosanoids come from

arachidonic acid

In the urea cycle, the second nitrogen of urea enters the cycle in the form of which of the following metabolites?

aspartate

overproduction of leukotrienes causes

asthma

rate limiting enzyme in urea biosynthesis is

carbomyl phosphate synthetase I

first function of vitamine b12

coenzyme for methylcobalamin in the formation of methionine from homcysteine

second function of vitamin b12

coenzyme in the transfer of methyl group from methylamalonyl-CoA to succinyl-CoA by adenosyl cobalamin

eicosanoids work by

connection to membrane receptors involved in g protein and calcium

Defective glycine degradation leads to

excess OAA production and thus one from of kidney stones

What are the functional parts of prostaglandin?

five carbon ring and hydroxyl group

what blocks THF regeneration

fluorouracil and methotrexate

In the urea cycle, ornithine transcarbamoylase catalyzes:

formation of citrulline from ornithine and another reactant.

The other forms of THF

formyl, methenyl, methylene, methyl

In the urea cycle, the carbon skeleton of aspartate is preserved as:

fumarate

oxidative deamination produces

glutamate

oxidative deamination enzyme

glutamate dehyrdogenase

Glutamine synthetase converts _____ to _____, whereas glutamate synthase converts _____ to _____.

glutamate; glutamine; α-ketoglutarate; glutamate

phosphoenolpyruvate is a product of? converts to

glycolysis. Phenylaline, tyrosine, tryptophan

pyruvate is a product of? and it can convert to

glycolysis. alanine, valine, leucine, isoleucine

3-phsophglycerate is a product of? converts to

glycolysis. serine -> glycine and cysteine

What is phospholipase activated by?

histamine and cytokines

defective methionine degradation causes

hyperhomocysteinemia, linked to blood clotting disorders and heart disease

The overall urea biosynthetic pathway takes place:

in both the mitochondria and the cytosol

The human genetic disease phenylketonuria (PKU) can result from:

inability to convert phenylalanine to tyrosine.

genetic disease PKU results from

inability to convert phenylalinine to tyrosine

enzyme in the formation of methionine from homcysteine

methylcobalamin

erythrose-4-phosphate is a product of? converts to

pentose phosphate pathway. Phenylaline, tyrosine, tryptophan

What breaks the off the chain of fatty acids

phopholipase

defective phenylalinine degradataion leads to

phylketonuria and albinis

thromboxine is synthesized in

platelets

eicosanoids are released from

polyunsaturated fatty acid

Four classes of eicosanoids

prostaglandins, thromboxanes, leukotrienes, lipoxins

What is Kwashiorkor

protein deficiency with starch diet

The coenzyme involved in a transaminase reaction is:

pyridoxal phosphate (PLP).

what is the enzyme involved in transamination

pyridoxal phsphate

The coenzyme required for all transaminations is derived from:

pyridoxine (vitamin B6).

Serine or cysteine may enter the citric acid cycle as acetyl-CoA after conversion to:

pyruvate

What happens when eicosanoids bind to their selective receptors?

regulate pro inflammatory processes

functional components of thromboxane

six member ring containing oxygen and hydroxl group

function of thromboxane

stimulate vasoconstriction and platelet aggregation (blood clotting)

lipoxins stimulates the production of

superoxidase anion which destroys inflammed cells

What is the main function of Glucocorticoids

suppress inflamation

functional components of leukotrienes

three conjugate double bonds

What is transamination?

transfer of amino group from an amino acid to a keto aacid

both glucogenic and ketogenic amino acids

tryptophan, isoleucine, threonine, phenylalnine, tyrosine

What is needed to form SAM

vitamin b12 and THF

Eicosanoids are derived from the following precursor:

Arachidonic acid

lipoxin is formed by

15 and 5 lipoxygenase

leukotrienes are formed by

5 lipoxygenase

Which of the following compounds can directly block thymidylate synthase activity?

5-Flourouracil

What is true about eicosanoids?

All eicosanoids are derived from a 20 carbon polyunsaturated fatty acid

What two enzymes make up prostaglandin endoperoxide synthase

COX and peroxidase

nonsteroidal antiinflammatory drugs inhibit

COX enzyme

What is one of the functions of prostacyclin?

Dilation of blood vessel

Which of the following compounds can release arachidonic acid?

Some membrane bound phospholipids

function of prostacyclin

inhibits platelet aggregation and stimulates vasodilation

what is marasmus

insufficient kilocalories and protein

The conversion of glutamate to an α-ketoacid and NH4+:

is catalyzed by glutamate dehydrogenase.

fumarate is used in

krebs cycle

oxyloacitate is a product of? and it can convert to

krebs cycle. aspartate which converts to asparagine, methionine, lysine, threonine -> isoleucine

a-ketoglutarate is a product of what? and it can convert to

krebs cycle. glutamate -> glutamine; proline and arginine

precursure to polyunsaturated fatty acid

linoleate from plant oil

Which of the following amino acids is/are ketogenic?

lysine

ketogenic amino acids

lysine, leucine

disfunctjion of branched chain a-keto acid dehydrogenase complex leads to

maple syrup urine disease

arachidonic acid is esterified to form

membrane phospholipid